The present invention relates to a liquid crystal display device; and, more particularly, the invention relates to a liquid crystal display device including a liquid crystal display panel and a back light disposed on the back side of the liquid crystal display panel.
A liquid crystal display device typically includes a panel made of transparent substrates disposed so as to be opposed to each other with a liquid crystal material interposed therebetween, and multiple pixels are formed in the area of the liquid crystal material. In this case, each of the pixels only has the function of controlling the amount of light being transmitted through the liquid crystal material, and does not itself emit light. For this reason, ordinarily, a backlight is disposed on the back side of the liquid crystal display panel.
This backlight is provided with not only a light source, but also a diffusing sheet and a reflector in order to cause the irradiation of light onto the liquid crystal display panel to be uniform. The light source uses a cold-cathode fluorescent tube (CFL) having a length approximately equal to the length of one side of the liquid crystal display panel, and is made to function as an illuminant by a voltage being applied to each of the electrodes formed to project from the opposite ends of the tube. However, in the liquid crystal display device having such a construction, the life of the light source is not sufficient, and it is no exaggeration to say that the life of the liquid crystal display device is determined by the life of the light source.
Specifically, during the lighting of the cold-cathode fluorescent tube, an electrode substance inside the tube is sputtered, and the electrode substance sticks to the tube wall. This electrode substance can be recognized as a black substance from the outside of the tube. The electrode substance which is stuck to the tube wall is alloyed (forms an amalgam) with mercury in the tube, and the consumption of mercury leads to the end of the life of the cold-cathode fluorescent tube.